A landlocked population of blueback herring (Alosa aestivalis) was established in 1982 in Lake Theo, Texas, and persisted for 7 years. Analysis of scales provided inaccurate ages for fish older than age 1. Analysis of otoliths provided valid ages of blueback herring, but protracted formation of annuli on otoliths limited the use of otoliths for back-calculating lengths of these fish. Fish in this landlocked population attained maximum total lengths of 240 mm, lived 2 years, and spawned only once. The disappearance of blueback herring in Lake Theo was attributed to their short life cycle and production of weak year classes. Future use of blueback herring as a forage fish may require additional stocking to supplement weak or missing year classes to maintain the population.